Hydraulic device



R. A. HENNING HYDRAULIC DEVICE Filed July 18, 194].

mil II Patented May 12, 1942 i I I UNITED STATES PATENT OFFICE HYDRAULIC DEVICE Raymond A. Hennlng, Piru, Calif asslgnor of seventy-five per cent to Charles S. Johnson, Piru, Calif. 7

Application July 18, 1941, Serial No. 402,978

' Claims. (01. 188-94) This invention relates to hydraulic devices in cylinder, but this guide is not packed. A small which liquid is recurrently transferred back and breather hole I!) may be provided in the upper .forth between a cylinder and a reservoir to conportion of the right end of the cylinder to pertrol movement of a piston in the cylinder. mit air pressure in the right end of the cylinder A broad object of the invention is to prevent 5 to equalize following movement of the piston 3. loss of fluid in a hydraulic system ofthe type A pipe 20 communicates the lower, right end pordescribed. tion of the cylinder 2 with the reservoir l2. Thus A more specific object is to prevent loss of fluid the pipe 20 is shown extended into a filler pipe in a system of the type described without re- 2| on the reservoir, which filler pipe is normally sorting to the use of packed joints between movclosed at its upper end by a plug 22.

mg parts. v The structure described functions as follows: The manner in which the foregoing object W n v e p ts 6 and 8 a m v d aw y are attained will now be explained by describing f o ea e by the operation of the est in detail an application of the invention to a of t e s ap mechanism, not s e piston hydraulic lock as depicted in the single figure 3 is withdrawn from the left end of the cylinder of the attached drawing. and draws in liquid from the reservoir l2 through Referring to the drawing a hydraulic unit I, the p pe the p 3 past the check valve M in accordance with the invention, comprises a d through the pas l s long cylinder 2 having a piston 3 therein secured t a as the valve I0 isclosed, return movement of the piston rod 4, which extends through the right parts 6 and 8 toward each other is prevented y end of the cylinder 2 and is connected by. a clevis the liquid filling the .left end of the y de 5 to a member 6. The cylinder 2 has an extenwever, when it is desired t p t the Parts sion I on its leftv end which is pivotally secured 5 and 8 to again approach each O e Va ve to a member 8. I0 is opened by pulling on the rod I6, which per- The members 6 and a happen t t t t 5 mits free return of the liquid from the cylinder relatively movable 'members of a scraper which gh the passa s 9 and I0 backinto the I are movable toward and away from each other reservoir to control the action of the scraper. It is desir- The Piston 3 y be P k n as Shown in able under certain conditions to be able t sepd a i e. t is pe i c i s a p i of arate the members 6 and 8 and to hold them oppositely facing Piston cups 3!! and 3 HOW- separated against substantial forces that are ever, it quite Often pp s t at after considergenerated by th scraper; The device able service pistons of this type are no longer stitutes a hydraulic lock which permits the mem- Perfectly tight, and some leakage of liquid bers 6 and 8 to be moved'apart and held against curs Pasf the Piston from the left end into the return by fluid confined in the cylinder 2 be- 5- risht end of the cylinder vThe present inventween the left end thereof and t p t 3 tion prevents the loss of this liquid, by return- Thus the left end of the cylinder 2 communimg it to the reservoir before it n ccumue t thrgugh a passage 9 a manually operated late in any appreciable amount. This return valve l0, and a pipe II, with the bottom of a is efiected through the Pipe-2- liquid r r ir I! hi is mounted on and 40 -Thus, assume that a small amount of liquid formed integrally with the cylinder 2. A pipe '3 has leaked past the piston 3 and accumulated in and a check valve l4 provide a by-pass around the bottom of the right end of the cylinder the manual valve 1 for fl w of fl id in one 2. Now assume that in accordance with normal dir ti only, namely from t reservoir 12 operation of the device the members 6 and 8 are t the cylinder Reverse fl w fro the moved away from each other, causing the piston inder back into the reservoir cannot occur un- 3 move to the right relative to the cylinder l t manual valve 3 is open. This valve is 2. This draws liquid from the reservoir I2 into.

shown as having a control arm l5 that may be the left end of the cylinder 2, as previously .controlled from a distance through a rod scribed. The movement of the liquid out of the A tension spring n normally maintains the reservoir produces a suction through the conduit valv lo ed, a 20 to draw any liquid in the right end of the The right end of the cylinder 2, through whi h cylinder back into the reservoir l2. The amount the piston rod 4 passes, is preferably provided of liquid h m y v ula d in the with a re-entrant guide l8 of substantial length right end of the c ylinder is usually very limited, for maintaining the rod in alignment with the and following the discharge of this liquid, air

ment, some liquid may be'sloshed from the reser voir I2 through the pipe 20, into the right end of the cylinder 2. However, this is not objectionable, sirice the liquid will be returned to the reservoir during the normal operation of the device, as

previously described.

As shown, the cylinder 2 is positioned substantially horizontally, and the right end of the cylinder is closed except for the vent hole l9 and theclearance around the piston rod a, where it passes through the re-entrant guide I8. So long as the cylinder is horizontal, a relatively large amount of liquid would have to accumulate in the right end of the cylinder before it could flow out through the piston rod guide It. Leakage of liquidthrough the guide I8 is further inhibited, even should the cylinder dip at the right end, by the re-entrant character of the guide it, whereby itextends inwardly away from the end of the cylinder. I

It is to be understood that although for the purpose of explaining the invention a specific application thereof has been described in detail, the invention is not limited to hydraulic locks of the particular type described, but is of general application in any hydraulic device where liquid is recurrently transferred between a reservoir and one end of a cylinder. The invention is, therefore, to be limited only as set forth in the appended claims.

' Iclaim:

1. In a hydraulic device comprising a cylinder having a piston movable therein, a closed liquid reservoir and fluid connection means for movement of liquid between said reservoir and one end of said cylinder accompanied by movement of the piston in the cylinder, the construction including a conduit extending from the lower part of the other end of said cylinder to the upper portion of said reservoir, whereby movement or said piston through one end of said cylinder, a liquid resermen toward said other end of said cylinder draws liquid out of said reservoir into said oneend of said cylinder, thereby producing a suctionin said conthrough one end of said cylinder, a liquid reservoir, liquid connection means between said reservoir and the other end of said cylinder, and means connecting the lower part of said cylinder adjacent said one end to the upper part of said reservoir, the end wall in said one end of said cylinder having a reentrant piston rod guide for inhibiting leakage of liquid through said guide around said piston rod.

- 5. In combination, a hydraulic cylinder having a piston therein and a piston rod extending voir partially filled with. liquid, liquid connection means connecting the lower portion of said reservoir with the other endof said cylinder whereby reciprocation of said pistonis accompanied by flow of liquid between the reservoir and said other end of said cylinder, and auxiliary connecting means connecting said one end of said cylin-' RAYMOND A. HENNING. 

